Senior Mechanical Engineer - Structures & Alignment

Company Overview

Mainspring Energy is revolutionizing power generation with the world’s most flexible and adaptable local power generation technology, the Mainspring Linear Generator. Commercial, industrial, and utility leaders are choosing Mainspring over traditional options like engines, turbines, and fuel cells to quickly and reliably deliver local power for EV charging, commercial facilities, data centers, and grid-scale operations.

The Mainspring Linear Generator is fuel flexible, ramps up and down to meet demand, and utilizes a flameless reaction with near-zero NOx emissions. Backed by top-tier investors including Khosla Ventures, Bill Gates, American Electric Power, Lightrock, and General Catalyst, Mainspring designs, manufactures and delivers its products to customers across the U.S. today, and we’re quickly scaling for international expansion.

Inspired by our vision of the affordable, reliable, net‑zero carbon grid, Mainspring is rapidly expanding within the $816B global electricity equipment market, and we’re hiring the best talent to meet growing customer demand around the globe. We welcome a broad range of backgrounds, experiences, and talents to bring fresh perspectives and ongoing innovation to our customers.

Pragmatic Optimism. Building a new category of world‑class power generation requires the optimism of ambition and creativity, balanced with practicality to solve problems efficiently. The challenges that arise are opportunities for growth.

Excellence without Ego. We bring expertise and commitment to creating the best customer experience, from sales to deployment and service, just as we apply deep technical rigor to building and delivering world‑class products. We strive for excellence and behave as leaders with the humility to acknowledge our challenges, both collectively and as individual contributors.

Proactive Collaboration. The integration and cross‑disciplinary nature of Mainspring’s business requires intentionally seeking out others who bring different skills, perspectives, and priorities. Our culture of inclusion and respect extends beyond our team to interactions with our partners and customers.

Mainspring’s Linear Generator is fundamentally different from a traditional engine.

Instead of rotary motion and a crankshaft, our system converts linear oscillation directly into electricity
. A low‑temperature, flameless reaction accelerates pistons and its translator shaft wrapped with permanent magnets through stator coils. Air‑spring chambers reverse the motion — generating power with high efficiency and ultra‑low emissions.

Critically, the translator shaft and pistons float on precision air bearings
, riding on a thin film of pressurized air. This minimizes friction and wear — but it also removes rigid mechanical constraints. The translator must remain precisely aligned within tight tolerances across the full cylinder length while traveling at resonance under dynamic loads.

This architecture is elegant — and mechanically unforgiving.

• Lead structural design and alignment strategy for alignment‑critical components
• Design and validate bolted joints under cyclic and thermal loading
• Develop GD&T and tolerance stack strategies across subsystem interfaces
• Own 3D CAD (Solid Works) and structural FEA (ANSYS or equivalent)
• Model structural behavior under vibration and thermal gradients
• Plan and execute durability testing and structured root cause investigations
• Translate test and field data into improved design standards
• Partner with Electrical, Controls, and Manufacturing teams to ensure scalable robustness

• Degree in Mechanical Engineering or a similar engineering field from an accredited institution. Experience and degree will determine level; minimum requirements are: BS + 12 years experience or MS + 10 years experience
• Delivered products as a technical lead through 3+ full design life cycles from concept to manufacturing support, preferably with product in high vibration environments with large cyclic loading
• Expertise in bolted joints, thermal impact on structures, design and analysis for severe…